The invention relates to an arrangement for detachably mounting an examining member onto a microscope.
Various examining members are mounted as required onto a microscope, including a stage for placing an object to be examined thereon, a condenser lens for collecting an illuminating beam of light, a holder for detachably retaining a filter, a phase contrast unit, auxiliary optical lens or the like. In the case of a stage, there are a number of types of stages, including a square crisscross stage which is driven by the use of a screw and a rack, a circular rotary stage, a manually operated gliding stage or an immovable plane stage, which are interchanged depending upon the desired manner of observation. Thus it is necessary that the mounting and removal of an examining member onto the body of the microscope be facilitated and efficiently made. A conventional arrangement for interchanging such examining members comprises a vertical dovetail construction for moving an examining member vertically relative to the body of the microscope, as illustrated in FIG. 1, which shows such construction for a circular rotary stage. In FIG. 1, the microscope shown includes a body 1 which is provided with an operating knob 2 for vertically moving a stage support 3 therealong. As shown in FIG. 2, the support 3 includes an examining member mount 51 in which a dovetail key 3a is formed. An attachment 4 is secured to a stage 5, and includes a stage attaching portion 41 which comprises a dovetail groove 4a that is adapted to provide a close fit with the dovetail key 3a, as shown in FIG. 3. The mount 51 and the stage attaching portion 41 essentially comprise a vertical dovetail connection mechanism.
The stage 5 can be mounted on the body 1 of the microscope by engaging the dovetail groove 4a with the dovetail key 3a and securing the attachment 4 to the support 3 by means of a set screw 6, and can be removed therefrom by a reverse procedure. The microscope body 1 includes a base 7 at its bottom and carries a lens barrel 10 at its top, the lens barrel including an objective assembly 8 and an eyepiece assembly 9. An object to be examined is placed on the stage 5, and can be observed through a lens 8a on a revolver 8 and through the eyepiece assembly 9. The revolver 8 comprises a turret so as to permit a change of objective lenses 8a, 8b for the purpose of varying the magnification. The stage 5 is further provided with a screw 5a which locks it against rotation.
With a stage mounting arrangement of such vertical dovetail type, when a stage is to be replaced, the set screw 6 is loosened and the stage 5 is moved upward relative to the body 1 for the purpose of removal therefrom. However, the distal end of the objective lenses 8a, 8b or the like presents a hindrance to such movement of the stage, and thus an inconvenience is experienced in that the operating knob 2 must be initially operated to lower the support 3 to its lowermost position before the dismounting can be effected. If the stage is dismounted from its fully lowered position, the stage 5 may inadvertently be struck against the distal end of the objective lenses 8a, 8b, resulting in a damage in the upper surface of the stage 5 or the expensive objective lenses 8a, 8b, even to a degree such that the objective lenses 8a, 8b may be rendered unusable. While it may appear that such disadvantages would be overcome by providing a sufficient spacing between the stage 5 and the distal end of the objective lenses 8 a, 8b when the stage 5 is in its lowermost position, this would result in an increased spacing between the base 7 of the microscope and the distal end of the objective lenses, with consequence that in use, the level of the stage 5 and hence of the eyepiece assembly 9 will be high enough to cause an inconvenience in the observation as well as a difficulty in carrying about the microscope.
As is recognized, a condenser must be disposed below the stage, and a filter or an auxiliary lens may be similarly provided as required in such position. Thus there is a need to secure a holding frame to the lower surface of the stage for holding a condenser, filter, auxiliary lens or the like, and the provision of such frame causes a further difficulty in the mounting and removal of the stage. With a metallurgical microscope, specimens are often ores of a relatively large size, which requires that a relatively large spacing be provided between the distal end of the objective lenses 8a, 8b and the stage 5, thus precluding the choice of an elevated position for the stage 5 in use.